Underwater exhaust



DOC. 22, D s wlLLY UNDERWATER EXHAUST 2 Sheets-Sheet l Filed Aug. 21

FIG

INVENTOR. DONALD S. WILLY ATTORNEYS Dec. 22, 1964 s, w Y 7 3,162,171

UNDERWATER EXHAUST 2 Sheets-Sheet 2 -48 r- I 0 I OJ I i 1" I FIG. 2

l I I & i I a I g I 45- i 54 i i T L I K l 54 i I I L i T Q i i 1 i E j5 i l 5 l I f l i i I l 45 I l i i l I l l I IN VENTOR. DONALD S. WILLYBY @M ATTORNEYS United States Patent Ofiice 3,162,171 Patented Dec. 22,1964 3,162,171 UNDERWATER EXHAUST Donald S. Willy, North Quincy, Mass.,assignor to Sui marine Research Laboratories, Inc, Everett, Mass., acorporation of Massachusetts Filed Aug. 21, 1962, Ser. No. 218,400 1Claim. (Cl. 115--.5)

This invention relates generally to exhaust systems for internalcombustion engines, and more particularly to demountable meansstructurally independent of a marine engine exhaust assembly fordirecting the exhaust gases under the surface of the water over whichthe vessel is passing.

In the construction of marine exhaust systems, two principal types haveheretofore been known. One such type is a dry exhaustsystem in which asuitable exhaust pipe is attached to the engine exhaust manifold and isusually positioned in a generally vertical fashion, being vented to theatmosphere. In such a system a conventional mutter is customarilyrequired to provide sufficient silencing. It is important that theexhaust pipe be not confined in any fashion to insure'that heatdissipated from the exhaust pipe and mufiler will not set fire toadjacent portions of the vessel.

A second type of marine exhaust system which is frequently employed is awet exhaust system. One of the limiting features of a dry exhaust systemis the difiiculty involved in locating the exhaust pipe in other than asubstantially vertically disposed position, so as to be in the open air,or in a ventilating stack. In a wet exhaust system the exhaust pipegenerally runs with a slight downward slope from the engine toward thestern of the vessel, terminating in a flange or fitting affixed to theouter face of the transom slightly above the water line. In such asystem it is necessary to add cooling water to the exhaust pipe in orderto prevent the pipe from becoming dangerously hot, with consequenthazard of igniting adjacent portions of the vessel. The cooling water isusually taken from the engine cooling system and introduced into theexhaust pipe aft of the exhaust manifold. A water trap may be providedin the exhaust system between the exhaust manifold and the point ofintroduction of the cooling water to prevent backflow of the water intothe engine.

The cooling water introduced into the exhaust system passes through thepipe and is discharged at the transom through the orifice formed at theend of the pipe. During operation of the engine the exhaust pipe isheated by the exhaust gases and a substantial portion of the coolingwater is converted .into steam. No mufier is generally employed in suchsystems since considerable mufiling or silencing is accomplished throughthe introduction of the cooling Water. During operation of the vessel,engine fumes and steam are consequently discharged from theexhaustsystem and can be observed rising from the stern of the vessel.When the wind is blowing from the proper direction, clouds of steam andexhaust fumes are swept over the stern producing an unpleasant conditionfor the occupants of the boat. In addition, there is apt to beobjectionable exhaust noise, as engines of high horsepower areincreasingly favored for power craft in order to achieve greater speed.

It is, accordingly, an object of this invention to provide an exhaustassembly for use with a wet exhaust system which will divert the exhaustgases under the surface of the water to silence the operation of theengine and simultaneously to reduce the presence of exhaust gases in thevicinity of the vessel.

It is a further object of this invention to provide an underwaterexhaust of the type described for use with a wet exhaust system whichwill not interfere with the safe operation of the engine nor willrequire modification of existing internal exhaust system structure.

It is likewise an important object of my invention to provide aneffective underwater exhaust discharge attachment which will handlelarge volumes of exhaust gas without diminishing engine performancethrough the development of excessive back pressure.

In the practice of my invention, in a preferred embodiment thereof, Iprovide a duct member adapted for installation over the dischargeorifice of a wet exhaust system which is normally located on theoutboard side of the transom. The duct member is preferably constructedof a resilient material and extends from the discharge orifice in agenerally vertical direction to a point located some distance below thesurface of the water. The duct memher is formed with an airfoilconfiguration to reduce drag and is cut away at its terminal portion tointroduce the exhaust gases into the water in the most efiicient fashionto minimize back pressure. Cavitation plates are provided below thewaterline to prevent the formation of an air column behind the ductduring forward movement of the vessel. Since the duct of my invention isattached to the outboard surface of the transom, no modification of theengine or internal engine exhaust system is required.

It is a feature of my invention that a high degree of silencing ofengine noises is achieved with an accompanying high degree of reductionof exhaust fumes and steam in the general stern area of the vessel.

It is a further feature of my invention that no baffles or similarstructures are employed in my silencer whereby nounwanted water will beretained in the system when the engine is stopped.

It is yet another feature of my invention that the duct of my inventionis constructed of a resilient material having shock resistantcharacteristics.

It is still a further feature of my invention that the duct of myinvention may be damaged, broken or removed without affecting the normaloperation of the engine or its exhaust system.

These and other objects and features of my invention will appear as thedescription proceeds with the aid of the accompanying drawings, inwhich:

FIG. 1 is a side view of an underwater exhaust according to my inventionshown in installed position;

FIG. 2 is an end view of my invention prior to installation;

FIG. 3 is a side view of the device of FIG. 2;

FIG. 4 is a section taken on the line 44 of FIG. 3; and

FIG. 5 is a section taken on the line 5-5 of FIG. 3.

Referring to FIG. 1 of the drawings for a more particular description ofmy invention in a preferred embodiment thereof, a fragmentary sternportion of a motor vessel 10 is shown. The motor vessel 10 includes abottom 12 and a transom 14. An exhaust pipe 16 is shown in its usualposition passing generally horizontally through the transom 14. It willbe understood that the exhaust pipe. 16 is part of a Wet exhaust systemin which cooling water is added to the exhaust pipe 16 to preventoverheating thereof. An end ring fitting or annular sealing flange 18 ispositioned about the exterior of the exhaust pipe 16 and fitted againstthe'outboard surface of the transom 14 to prevent the passage of waterinto the bilge. I

An exhaust duct member, indicated generally at 20, is shown afiixed tothe transom 14. In the preferred embodiment, the member 20 isconstructed of a resilient non-metallic material, as for examplene0prene,- rubber 'or the like. It will be understood, however, that themember 20 could be constructed of non-resilient material if the yieldingshock-resistant qualities hereinafter dc-.

scribed in my invention are not desired. The member a end of the exhaustpipe 16. The hemispherical chamber 22 communicates through its bottom 26with a substantially vertical duct .28. r

The. member 20 is provided at its upper end with. means for securing itto the transom 14 comprising an integral flange plate 30. A plurality ofspaced peripheral openings32 are provided through the flange plate 30'whereby the member 20 may be bolted: to the transom 14 of the vessel bybolts 34, which pass throughthetransom 14 and are'retained by nuts, 36.A. gasket 38 or other packing may be interposed between the flange plate30 and outboard surface of'the transom 14 if desired.

The hemispherical chamber 22 communicateswith the discharge orifice 24of the exhaust, pipe 16 through an opening indicatedgenerally at 40 in.the flange plate 30. The opening 40 is substantially the same radius, asthe hemispherical chamber 22 and may be provided with slightly outwardlyinclined terminalportions 42. The

size of the opening 40 is. initially selected to permit the member 20 tobe bolted. to the transom 14 by its flange plate 30 and. to completelycover the discharge orifice 24 of the exhaust pipe 16 and. the. annularsealing flange 18-.- In this fashion it is unnecessary to disturbormodify the existing exhaust system. A. substantial advantage is derivedthereby in that the member 20 may be removed at will fromv the vessel.without interfering. with the existing exhaust system and the safeoperation of the engine.

The member 20 has a generally outwardly and downwardly curved external uper portion 44 which merges into a downwardly extending lower portion46. A plurality of horizontal fins 48 are provided on the upper portion44 and extend, longitudinally from. the 'fia nge plate 30 to therearrnost portion of the upper portion 44. In the preferred embodimentthree such horizontal fins 48'are employed. Each fin 48 extendstransversely substantially the full width of the flange. plate 30 and isprovided with a rearward semi-circular edge 50. as is best seen in FIG.4. The horizontally extending fins 4.8

serve to absorb compression shocks which may be administered to. themember 20, as into adock.

The lower, substantiallyivertical portion 46 of the member 20' extendswhen installed six tov nine: inches below the bottom 12 of the boat.Since the height of the exhaust orifice 24 above the bottom 12 of thevessel will varyfrom case to.c.ase,the.member 20 is. initially forexample by backing 4 to breakup, deflect and dispel any air bubbleswhich may be formed during forward movement of the vessel.

The vertical passage 28 within the portion 46 extends the-entire lengththereof from the bottom 26 of the hemispherical chamber 22 to an'outletportion, indicated generally at 58 in FIG. 1. The outlet 58 isformed by first cutting the portion 46 horizontally from its trailingedge 45 approximately halfway through the passage 28 and by then cuttinglongitudinally up the member 46 from its bottom to the junction of. thefirst cut. This forms a rearward opening or outlet in the member 46through which the exhaust gases and steam are discharged under thewater. The adjacent forward portion of the. member 46 indicatedgenerally at 60, is not removed or cutv off at the time ,ofinstallation. Adjacent the outlet 583there therefore remains the portion60 with its: airfoil configuration including a leading edge 62. Thepresence. of the a portion 60 increases the flow of exhaust gases fromthe passage 28 by creating a slight reduction in pressure at the outlet58 during forward movement. by the vessel. It will be noted that thisreduction in. pressure is increased 7 as. the speed, of the vesselrelative to the water in- The exhaust gases will therefore be expelledof the creases. with substantially constant efiiciency as the speedvessel increases relative to the water.

A relief port 64 maybe provided in. the member 20 to vent thehemispherical chamber 22 to the atmosphere. As seen in FIG. 1, the port64 is locatedaat the side ofv the member 20 just below the uppermosthorizontal; fin. 48, whereby any spray rising. from the port 64 isdirected downwardly. The relief port 62(is not a, necessary element inmy invention but may be. useful where the vessels engine is locatedbelow the'water'line, under which conditions syphoning of waterco'uldoccur. The relief port 64 may also be desired where substantialback pressure is present in the system rendering enginestartingdiflicult. The relief port 64, which could be valved, may be:ap-

proximately /siinch in diameter and in no way interferes 40 with. theproper operation; ofv themember 20.

. member 20' from a resilient material as in the preferred It.should-also be noted that. the construction of the embodiment producesan additional advantage in that the 8 member 20;will be deflectedslightly by the water when a the. vessel is engaged in. a highspeedturn, thereby reducthe member 20 is also advantageous. in thatthe memberformed as seen in FIGS. 2, ai1d 3 to'includeza vertical.

portion 46 which extends substantiallyfurther than-is. normallyrequired. .Since the member. 20. is. constructed, in the preferredembodiment, from a resilient material, as for example neoprene,-it is aneasy inatter-forthe user to cut the member 20 to the proper length atthe time of I installation.

The member 46 has a generally,tear-drop configuration producingageneralt airfoil. shape-asfmay bemost clearly seen in FIG. ,5.. Theairfoil'shape greatly re duces the drag causedlby the portion. 46. vTheairfoil FIGS. 2. and 3.

of the boat.

20 can sustain. a degree of shock,[as for example when the vessel isbacked into a: dock or other object; .This resiliency is alsdvaluable inthatthe member 20 will not fracture when the. vessel. strikes asubmerged object, as forexampleabuoy;

- The installation of my exhaust assembly is as follows: J The member20'is initially constructed as shown-in- Theverticalportion 46 is firsttrimmed to extend. approximately 6" to' 9 inches below fthebottom- Theexhaust outlet- 58 is then cut: in the vertical portion 46 as abovedescribed. Theflangeplate 30 is bolted to the transom of thevesseliwith.the'bpening 40. leading to the hemispherical. chamber? 22Ipositioned=rover the exhaust orifice'24; As above 'noted, itis'unshape. alsogreatly reduces the possibility of theformationof a vertical air columnat the trailing edge .45 of the portion 46. 'Ihe'presenceof'such an aircolumn would? substantially defeat the operation of the member 20 sincethe steam and exhaust fumes would be permitted to ,risedirectlyto thesurface and would not be carried away underwater, nor would theeffective silencing. result. 'J

, 1 In order-to further eliminate theipossibility-of the formation' ofan' air column at, the trailing edge 45 of the.

portionff46, a plurality of horizontally extending cavitation" plates.54' are mounted on the-member 46.: A's'is 'most clearly seenin FIG. 5,ea chcavitation plate 54ex-f tendsrearwardly from the member 46 andterminates? in a rounded rear edge 56. The cavitation-plates 54 serve- Inecessaryto remove ,the' annular sealing flange. 18 normal ly positionedaboutfthe; exhaust orifice; 'The unit is then ready for operation. P A wa,

It will thus be observed that an underwater, exhaust is provided by myinvention'whichproducesahigh degree of engine silencing "and it highdegree fof reduction of exhaust fumes and steam by dischargingthe'fumesandsteam substantially below the surface. of the water wherethey maybe carried rearward thereof. In theevent of damagesustainedto;th e underwaterexhaust of;my invention ituis furthergpo'ssible toremove it-f'romthe W 5 i Without interfering" with the safe operationthe engine. 1 v

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

An exhaust silencer device for a motor vessel having a hull throughwhich an exhaust pipe for an inboard engine extends in a generallyhorizontal direction in the vicinity of the waterline of the vessel fordischarge into the open air, said device comprising a body having agenerally horizontal inlet passage and a generally vertical passage incommunication therewith, the body having a flange for securing thedevice to the hull of the vessel over the open end of the exhaust pipeoutwardly thereof with the inlet passage of the body aligned with thedischarge passage of the exhaust pipe, the body of the device extendingdownwardly from the hull of the vessel to a region below the surface ofthe water when the vessel is under way, the cross-sectionalconfiguration of the body below the surface of the water being elongatedin a fore and aft direction of the vessel, the body tapering toward itsleading and trailing edges from a region intermediate said edges, thebody at its bottom end being deeper toward its tapered fore part than inthe trailing portion, the exhaust gas discharge passage extending vertically downward through the bottom of the body through both the deeperfore part and the trailing portion of said body.

References Cited by the Examiner UNITED STATES PATENTS 2,111,325 3/38Linthwaite 115-17 2,681,029 6/54 Canazzi 1l5--34 MILTON BUCHLER, PrimaryExaminer.

ANDREW H. FARRELL, Examiner.

